Interaction between circulating amyloid fibril protein precursors and extracellular tissue matrix components in the pathogenesis of systemic amyloidosis.

Amyloidosis is a heterogeneous group of diseases characterized by deposition of a fibrillar, proteinaceous material, amyloid, in various tissues and organs. Increasing knowledge about the different proteins that constitute the amyloid fibrils has made it possible to classify amyloidosis by the fibril protein, which appears more rational than the traditional classification by its clinical expression. A serum protein is the precursor of the amyloid fibril protein in the various systemic forms of amyloidosis. Although the chemical composition of amyloid is presently well known, the pathogenetic processes that convert such proteins into a fibrillar form and lay them down in the tissues are far from clarified. We suggest some pathogenetic mechanisms for amyloid deposition, involving different types of fibril protein, their precursors, the extra-fibrillar amyloid P component, glycosaminoglycans, proteoglycans, and calcium with special reference to experimental work from our research group.